Blog/ Hospital auditing
Retrospective audit: what it is and how it reduces denials
Performed after the patient’s discharge, a retrospective audit reviews the entire hospital claim. See how the process works, how it differs from concurrent audit and how it strengthens hospital billing
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- Rivio, Editorial team
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- 6 minutes
Retrospective audit is the process of reviewing the hospital claim after the patient’s discharge, when all clinical and financial documentation has been closed. Unlike other types of audit, it analyzes the complete case, from the beginning to the end of care, cross-checking the medical record, prescriptions and charges in a single review.
This format offers a broad view of care, but it also has an important limitation: any failures are only identified after the fact.
Understanding how retrospective audit works, how it differs from other types and how it affects billing helps hospitals use this tool strategically within the broader process of hospital auditing, not just as a corrective measure.
What retrospective audit is
Retrospective audit is a complete review of the hospital claim after the patient’s discharge and the closing of the medical record. The auditor, a physician or nurse with specific training, checks whether the procedures billed match what was actually recorded in the clinical documentation.
This type of audit can be performed by the hospital’s own team, as a preventive internal audit before the claim is sent to the payer, or by the payer, after receiving the invoice. In both cases, the goal is the same: to verify that the care provided and the amount billed are consistent.
Because it happens after the case is closed, retrospective audit depends entirely on the quality of the documentation produced during the hospital stay. Incomplete medical records or poorly recorded prescriptions make the review harder and increase the risk of denial.
How retrospective audit works in practice
The process begins with a review of the complete medical record, cross-checking each procedure performed against what was billed on the claim. The auditor checks billing codes, materials used, medications administered and whether the clinical progress notes are consistent with the items billed.
When a discrepancy is identified, the auditor flags the item for correction or denial, depending on who is conducting the review. When the audit is internal, the billing team corrects the claim before submission. When it is done by the payer, the discrepancy results in a formal denial, which the hospital can dispute through an appeal.
The time between discharge and submission of the claim to the payer follows minimum parameters set by Brazil’s National Supplementary Health Agency (ANS) in Normative Resolution No. 428/2017, which regulates authorization and denial processes between providers and payers. Each contract may set specific deadlines within these parameters, which is why a fast retrospective audit matters.
Retrospective audit vs. concurrent audit
The main difference between the two types lies in when the audit takes place. While retrospective audit reviews a case that is already closed, concurrent audit takes place during the hospital stay, allowing corrections in real time.
| Criterion | Retrospective audit | Concurrent audit |
|---|---|---|
| Timing | After the patient’s discharge, with the case closed | During the hospital stay, in real time |
| Goal | Review the complete case and identify patterns | Correct discrepancies before the claim is closed |
| Speed of correction | Lower; the denial may have already occurred | Higher; prevents the denial before it happens |
| Main use | Management indicators and future prevention | Immediate denial prevention |
Hospitals that combine both approaches can reduce avoidable denials during the hospital stay and still have the complete view that only retrospective audit offers after discharge. Prospective audit, performed before care is delivered, completes the set by acting on the prior authorization of procedures.
Advantages and limits of retrospective audit
The main advantage of retrospective audit is the complete view of care. Because it happens after the case is closed, the auditor has access to all the documentation, which makes it possible to identify error patterns that would go unnoticed in a one‑off review.
This retrospective data also feeds management indicators, showing which types of denial recur, which specialties or procedures have the highest discrepancy rates and where clinical documentation needs to improve. Knowing the types of hospital audit helps the hospital decide when to apply each one.
The limit of retrospective audit lies in its timing. Because the review is done after discharge, any failures have already happened, and the correction only prevents the same error from recurring in the next case. That is why it works best as a complement to concurrent and prospective audit, not as the only line of defense against denials.
Impact of retrospective audit on billing and denials
According to the Anahp Observatory 2025 (National Association of Private Hospitals), the accepted denial rate as a share of gross revenue jumped from 0.78% in 2021 to 1.96% in 2024, more than doubling in three years. Some of these denials stem from documentation failures that a well-structured hospital claims audit can identify and correct before the claim is submitted.
ANS Normative Resolution No. 503/2022 requires contracts between payers and providers to be formalized in writing, with specific clauses on how denials are handled. This reinforces the need to align retrospective audit with each payer’s contractual rules, since appeal deadlines and criteria vary according to what was negotiated.
Hospitals that treat retrospective audit as a source of data, not just as a review step, can turn the patterns they identify into preventive actions, reducing denials in subsequent cycles. Looking up how much it costs to audit a medical claim helps size the investment in this routine.
Retrospective audit supports decisions, but does not replace prevention
Retrospective audit remains essential for hospital billing, but its greatest value lies in the data it generates, not just in the denials it prevents after the fact. Using that data to adjust processes and documentation reduces the volume of discrepancies in the next cycle.
Artificial intelligence tools already help hospitals move this process earlier, cross-checking clinical data against billing rules in real time and reducing reliance on corrections made only after discharge.
Frequently asked questions about retrospective audit
What is the difference between retrospective and concurrent audit?
Retrospective audit reviews the claim after the patient’s discharge, once the case is closed. Concurrent audit takes place during the hospital stay, making it possible to correct discrepancies before the claim is closed.
Who performs retrospective audits?
They can be done by the hospital’s internal team, before the claim is sent to the payer, or by the payer itself, after receiving the invoice. In both cases, the auditor is usually a physician or nurse with specific training in auditing.
Does retrospective audit prevent denials?
When done internally, it helps identify and correct discrepancies before the claim is submitted, but it does not prevent denials applied by the payer after it receives the invoice. Its greatest value lies in generating data to prevent future errors.
How long after discharge is the retrospective audit done?
There is no single deadline: each payer sets it in the contract, within the minimum parameters established by ANS Normative Resolution No. 428/2017 for processes between providers and payers.
Does retrospective audit replace concurrent audit?
No. The two types complement each other: concurrent audit corrects in real time during the hospital stay, while retrospective audit offers a complete view of the closed case and feeds management indicators.
